On Sentience and Shopping Carts
by Katadenza
Summary: Kaito becomes philosophical again in the supermarket, while Miku has her own hidden agenda. Sequel to On Mortality and Melted Ice Cream. One-shot.


**Author's Note:** If you look very closely, you can see the exact moment where the amateur philosophy ends and the shameless fluff begins. At least, I think you can. I certainly can't.

 **This fic is set in the Labyrinth-verse.** (More info on my profile, if you're interested in that sort of thing.)

Fun Fact: If it isn't obvious now, this fic was supposed to be published six months ago for a certain other Vocaloid's birthday. Whoops. I've already started writing a birthday fic for Miku, though, and I'll get it published in the next 24 hours I _swear_. Or at least I won't wait a whole six months next time. I hope.

And as always, concrit is welcome. Happy reading!

* * *

 **FEBRUARY 16, 2015**

* * *

No matter how hard Miku stared at the scrap of torn notebook paper, she somehow couldn't will the shopping list into being even _slightly_ shorter.

Out of the corner of her eye, she saw Kaito dump an armload of various cleaning products into the shopping cart with great difficulty. Stretching a bit, he eyed the massive pile of items already in the cart worriedly. "Are you sure you don't want me to push that?" he asked, pointing at the cart.

Miku reflexively tightened her grip on the cart handle. "No," she said. "You're _not_ exerting yourself today. Didn't we agree on this?" _Cleaning stuff done_ , she mentally checked off the list. _Now for the food._ She nearly shuddered. Feeding a manor full of Vocaloids was never easy, especially with all the new kids running around.

Kaito grumbled, adjusting his scarf. "C'mon, I think I'm at ninety percent. I can do it." All the same, he took a glance at the shopping list in Miku's hand and immediately made a beeline for the Frozen Foods and Vegetables section of the supermarket.

Pushing the cart after him with a bit of effort, Miku called, "If you start pushing this thing, you'll be hitting ten after five minutes." Parking it next to a plastic crate of ginger, she made her way over Kaito, who was by then inspecting nearby crate of celery.

Taking one of the vegetables in his hand, Kaito pointed it dramatically at the approaching Vocaloid. "You _dare_ underestimate my power?" he cried, brandishing it through the air.

Miku rolled her eyes. "And I thought you were supposed to be the careful one." Gently removing the celery from his grasp (making sure to put it in the right place), she then started taking fifteen oranges, no more, no less, from the crate right next to it. She was under Meiko's strict orders to be precise, _very_ precise about what they threw in the cart. Money was tight after all, due to said new kids. And she wouldn't _dare_ disobey Meiko's orders.

Miku looked up momentarily after hearing the sound of footsteps. She found Kaito holding a small white plastic cup of ice cream and looking enraptured. Incredulous, Miku could only ask, "How... where... did you...?"

"They were giving out free samples!" Kaito grinned, nearly bursting from energy. "I think I'm at ninety-five now! Now will you let me push the cart?"

"You can't have gotten five percent from that tiny cup of ice cream..." Miku said in disbelief. In spite of herself, she started craning her neck in search of the one giving out those free samples. She could use some ice cream herself.

Kaito sighed and shook his head in mock disapproval. "Now you're underestimating ice cream? For shame, Miku, for shame. After _everything_ we've been through..."

"Shut up."

"Hey, the numbers don't lie," Kaito said, making a big show of waving around his translucent scarf, the number "95" on one end glowing a soft, calming green. "Besides, look who's talking. How much energy do _you_ have left?"

Miku desperately tried not to make eye contact. "F-forty seven," she stuttered. "W-what about it?"

Before Miku could even blink, Kaito had taken control of the the unguarded cart in one smooth movement. "I rest my case."

"Hey!" Miku managed to beat him away from the cart with an orange. "I'm not passing out yet, am I? Anyway, I know I'll last longer than you."

"You break my heart, Miku."

"You do that to yourself," she snorted.

Kaito, resigned, leaned back against the crate. "It just doesn't seem fair, with me being at ninety-five and you being at fourty-seven. I feel like a bad friend."

Miku finally managed to haul all the oranges into the packed cart. "Make it up to me by getting the vegetables, then," she panted. "I'll deal with the fruits."

Kaito didn't move from his spot as he stared up at the ceiling with no discernible expression. "Oh, don't worry, I'm _definitely_ going to make it up to you later."

"What?"

"It's an off-day tomorrow, isn't it?

It took a few seconds for Miku to get it.

She blushed furiously, turning as red as a nearby crate of tomatoes. Mortified, she rapidly checked their surroundings for any possible witnesses. Finding none, she gave him several small punches on the arm, whispering through gritted teeth. "Kaito, we're in public!"

Kaito could only laugh at the flustered Vocaloid, not really trying to fend off her punches. "Okay, okay, calm down. What are those vegetables we needed again?"

Miku practically shoved the list into his hands, trying to slow down her frantic heart from sheer force of will. "Someone could have heard that, Kaito!"

"But no one did, did they?" Kaito winked at her, giving the list back. Suddenly, he leaned in, dropping his voice to a whisper, "I'm serious about later though." He then strutted off, leaving Miku even more flustered and seething than before. _Damn him_ , she thought. _Damn him._

After Kaito came back with the vegetables (with extra spring onions), and after Miku had finally pulled herself together, the two finally made their way over to the frozen foods area. As the two Vocaloids wandered among the rows and rows of freezers, Miku noticed that Kaito had been unusually quiet (by now he should have been bouncing off the walls in excitement, it _was_ his favorite part of the store). But now he seemed lost in thought, looking somewhere in the distance while his mind was somewhere else entirely. Miku didn't try to drag him out of his reverie. Among all the time they've spent together, she liked these moments of comfortable silence the most, nothing but the two of them and the sound of their own footsteps.

However, she still took the opportunity to glance at a secret list she had written on an even tinier scrap of paper, scanning it frantically. She was already halfway through. Now, if she could just keep him from noticing...

Kaito suddenly broke the silence, forcing Miku to stuff the list back into her pocket, looking twice to make sure it was the secret one. "Hey Miku, I've been thinking-"

"That's a surprise," she said automatically. It earned her a swat on the shoulder and a small glare. She giggled.

"That's getting old," he grumbled. "But anyway, I've been thinking, we've done this countless times now, haven't we?"

"Yeah...?" Miku answered, opening a freezer.

"Don't you think it's a bit... automatic for us to do this by now?" He turned away from her, looking at the rest of the store.

"If you mean that we can do this in our sleep, yes," Miku said, trying to figure out how to sneak in an extra tub of ice cream into the cart.

Kaito suddenly looked back, forcing Miku to shut the freezer door and try to look innocent. "But when do _you_ ever sleep?" he teased.

Miku rolled her eyes. "You were about to make a point. Go on."

"Hey, it's not _my_ fault that Songbird's a night owl."

"MOVING ON," she sputtered, blushing.

Kaito laughed, looking away again. Miku took the opportunity to shove the tub (vanilla with a chocolate swirl) into the cart as fast as she could.

"Anyway, we do this a lot right?" he continued, leaning back on the cart. "When you think about it, what are we _really_ doing?"

"Making sure Mei-chan doesn't kill us?"

Kaito pouted. "Seriously, Miku."

"I dunno, um..." Miku shrugged. "Shopping for groceries? What else?" There was also the _other thing_ she was doing, but of course, she didn't say that out loud.

"Well, you're not wrong, but-" He gently tugged the list out of her hands, gesturing at the writing. "When you break it down, did you know all we're doing is just reading what items to find, finding them, and putting them in a cart?"

"First, give that back. I'm trying to buy Luka-nee's tuna. Second, your point is...?"

Kaito sighed as he handed the list back to her. "I'm just saying that it seems too... thoughtless. Robotic, even. Also, I don't think that's going to fit in the cart."

Miku was attempting to heave the extremely large fish into whatever space was still available. "If it doesn't fit," she grunted, "I'll _make_ it fit." Kaito rapidly came to her assistance, taking on half of the strain as the two managed to lift it into the nearly overflowing cart. Miku took a deep breath afterwards, wiping her hands on her skirt. "Also, aren't we already, you know, robots?"

"That's not it! It's just-" Kaito struggled to find the proper words as they left the freezers behind. "When you think about it, it's like _anyone_ , even robots Master can program in an hour, can do what we're doing."

"I don't think Master would agree that programming _any_ robot will take just an hour," Miku said with a small smile. In her head she went over the secret list again, taking herself in what was hopefully the right direction.

"But you see where I'm going right?" Kaito asked as they walked into an aisle with baking supplies.

"Not really," Miku admitted, eyeing a box of gelatin.

Kaito exhaled, gripping the side of the cart. "Okay. So I was thinking, if supposedly non-sentient laborbots are capable of doing what we supposedly sentient Vocaloids can, then what's the difference?"

The question hung in the air, unlike the box of gelatin which dropped right into the cart from Miku's hand.

"So you're saying..." Miku said, leaning onto the cart handle. "That we're not sentient? That's it?"

"No! I mean, yes! I mean-" Kaito nervously tugged at his scarf. "Maybe?" He shook his head. "I guess I'm just trying to figure out if the word "sentient" even means anything."

Miku cocked her head. "It seems pretty simple to me," she said, pushing the cart forward. "Rocks aren't sentient. Humans are. I don't see what makes this so complicated."

Kaito placed himself at the front of the cart to face Miku, walking backwards as they went. "I'm not talking about rocks, Miku," he said. "I'm talking about _us_."

"Well, Master's going to be really disappointed if we aren't as sentient as he says we are," Miku said as she stopped in front of a shelf of vanilla extract. "If the chip in our heads-"

"If the chip in our heads is the only thing making us different from rocks and laborbots, then I'm not sure if it really is much of a difference," Kaito said. Miku saw that he was beginning to look alarmingly sad.

"It does!" Miku cried, louder than she meant to but not really caring. "It's like the numbers between zero and one, that's an entire infinity of difference," she said, desperately wanting to chase away the despondent look on his face.

Kaito didn't look her in the eye. "Did you know," he said. "That the fact we could comprehend a state between zero and one was used to prove we were different from ordinary computers?" He smiled a bit, but then his head fell and he seemed to slump over the edge of the cart.

Miku couldn't stand it anymore. She raced to join Kaito at the other end of the cart, laying a comforting hand on his arm. "Hey... How did you suddenly end up thinking about this anyway? I thought we were supposed to be grocery shopping." She smiled a bit, trying to get him to cheer up.

"That's exactly it," said Kaito. He straightened up, leaning over to the shelf to grab a bottle of vanilla extract. "Look at this. You know what it is, right?" he asked, holding it in front of Miku's face.

"Uh, yeah?"

"It's on the list, right?"

Suddenly, Miku was brought back to the _other_ thing she was doing. She tried not to look too nervous and hid the list behind her back. Hopefully, he would be too enamored with his explanation to ask Miku to let him actually see it.

And technically, vanilla extract _was_ on a list...

"Yes," she answered.

Wordlessly, he dropped the bottle into the cart. "Do you see how easy it was? You just needed to answer two yes-or-no questions. You almost didn't need to think."

"And what's so wrong with that?"

"I thought that at first, but then I realized you could apply that to _everything_ we do," Kaito said, flinging his arms outwards.

Miku raised an eyebrow. "Really?" She took control of the cart again, slowly making her way out of the aisle and into another. Kaito was at her side, walking in step with her.

"Think about it. Do our systems say we're low on energy?" he said, idly inspecting a box of cookies. "We eat or sleep."

Miku was trying to decide exactly how many spray cans of whipped cream she needed. One was probably enough. "That's it?"

"Nope. Do we sense something that could harm us? We try to avoid it."

Miku tried to look nonchalant as she tossed the can into the cart. "I know we start running like hell when Mei-chan starts screaming, but how is that-?"

"I have one more. When we're singing for producers-"

Miku halted abruptly, then made a sharp half-turn to face him. "How does SINGING qualify for this?"

Kaito smiled sadly as he put the box down. "In the end, you'll have agree with me when I say all we're doing is just sounding out an arrangement of phonemes uploaded to our processors. Right?"

"Well..." She knew he was right, but at the same time dead wrong. Miku struggled to come up with something to counter, that she _knew_ (and he did as well) that there was always something more than that. "But..."

Kaito sighed. "So I guess, if we aren't as sentient as Master thought we were, then I guess there's nothing stopping humans from doing whatever they liked with us."

Miku stopped in her tracks, horror-struck. "Kaito! That's not-!"

"You can't come up with anything that proves otherwise, can't you?"

Miku hated it, but she knew he was right.

The two lapsed into silence as they walked to the check-out. It wasn't the peaceful, comfortable kind she liked this time, and her mind raced as she tried to think of something to say that would snap Kaito out of the mood he was in. But she really _wasn't_ good at this sort of thing like Kaito was, and try as she might she just couldn't find a way around his arguments.

They passed a shelf full of Valentine's Day chocolates, still unsold, with a sloppily added banner announcing they were all on sale for seventy-five percent off. Miku winced at the sight of them. She had never understood why humans (in this country at least), had come up with these commercially-motivated traditions in the first place.

Something clicked in her mind. Kaito looked at her strangely, noticing her expression. "Miku, what-?"

Miku swallowed, an idea already half-forming in her processors. "Kaito, you know all those things you said? Don't humans do those things too?" She could feel it was a weak argument, but it was something.

Kaito opened his mouth, but no words came out. He ended up closing it again, deep in thought.

Miku pressed on. "I mean... almost everything we do now, humans did first. What does this say about them?"

"So you're saying humans aren't sentient either?" asked Kaito.

"Maybe? I don't know," answered Miku. "What does being sentient even mean?" By now she could actually feel her processors beginning to hurt.

Kaito sighed. "This was a lot more complicated than I thought it would be."

"Tell me about it," Miku groaned. "Hey, why don't we focus on getting these groceries back to the Manor. I don't think Mei-chan would like it if we delayed any longer."

Kaito nodded. "Yeah, she won't."

But he didn't smile once when they paid for everything, not even laughing when they had to lift the enormous tuna out of the cart with great difficulty. His voice didn't stray anywhere from a monotone, and Miku had to call his attention several times before he would even respond.

He hadn't stopped thinking about it. Miku was concerned to see her best friend in such a state.

But she still had a plan. She just hoped it would work.

* * *

No matter how hard Miku stared at the sheet of paper, she somehow couldn't will the recipe into being even _slightly_ shorter.

Rubbing her temples, she sighed as she surveyed the kitchen table in the moonlight, seeing the various ingredients and equipment scattered all over. Off to the side, a misshapen cube of vanilla (with a chocolate swirl) ice cream was slowly melting in a baking pan.

Sucking a spot of whipped cream off her finger, she tried to see where she had gone wrong. It wasn't even that complicated to make, the website had said. Really easy, they said. A complete cooking klutz could do it, they said.

What a load of-

"Miku?"

Her head whipped around in the direction of the corridor, and she nearly knocked several bowls off the counter.

A confused-looking Kaito stood there, barefoot in his silk pajamas.

Miku scrambled to stand in front of the pan of melting ice cream, arms flailing. "I th-thought you were asleep!" she stuttered.

"I woke up and noticed you weren't in bed, so I checked the Music Room, but you weren't there either," Kaito said. "And then I heard someone in the kitchen, so..." He stepped forward, trying to get a look at what Miku was hiding. "What are you doing? Is that ice cream?"

Miku tried to push him back towards the corridor. "It's nothing! It's nothing! I'm just..."

Kaito pouted. "Just what?"

"I... uh..." Miku looked back and forth between Kaito and the counter. She sighed again, her hands falling to her sides. "You weren't supposed to know until morning..." she muttered.

"Songbird..." Kaito gently placed his hands on her shoulders. "What's going on?"

Miku shook his hands off, stepping backwards until she was right up against the counter. "Okay, okay..." she breathed, bringing a hand to her forehead. "Ah, I was supposed to have this whole speech prepared but-" She inhaled, clutching her hands together. "So, I'm sorry I wasn't able to give you anything last Valentine's Day."

"What? I told you it was okay, Miku. I knew you were busy-"

"I wasn't finished," Miku said. "I know you said it was okay, but I still felt pretty guilty about it given everything you've done for me. But I realized that it would be your birthday in a few days, and I didn't want you to have the monopoly on grand romantic gestures..."

Miku gulped and stepped aside, squeezing her eyes shut as she presented the baking pan with her arm. "So I decided to make you a cake. An ice cream cake. It's not really finished but I hope it's... good..."

She wanted to kick herself for that. Good? Really? But she made herself continue. "And I couldn't help but worry about what you said earlier, about us not being sentient. I didn't have the right words to fight that then, and I still don't, so I hoped this would help."

She took a deep breath, and took his hands, staring directly into his blue eyes. "I care about you, Kaito. I don't know if that proves anything about me, but I think it's enough. I hope it's enough."

Kaito didn't say anything, just stared. Miku, feeling increasingly nervous, let go of his hands and chattered to fill the awkward silence.

"I mean, I know I shouldn't have done this alone. It's not even a good cake. I should have asked Mei-chan for help. I'm so-ah!?"

She was suddenly enveloped in a bear hug, her face pressed into his shoulder. "I think it's a _wonderful_ cake," said Kaito, his voice trembling. "I don't think a laborbot could do anything like this. Thank you, Miku."

"Yeah..." Miku smiled as she hugged him back. "Happy birthday, Kaito."

She thought she could hear him sniffing. "Kaito, are you crying?"

Above her came a watery "N-no..."

She grinned. "Really?"

He pulled back, letting her see his tear-stained smile. "Maybe a little..."

Then he kissed her, and Miku understood exactly how the melting ice cream cake felt like as his arms tightened around her.

They came apart, and Kaito stared bemusedly at the baking pan. "Do you want me to put that in the freezer?" he asked, running his fingers through her hair. "I wouldn't want the cake you worked so hard on to turn into ice cream soup."

Miku, still slightly dazed, couldn't help but giggle.

"Sure."

 _ **fin.**_


End file.
